Conduits for design to carry cable (for example, conduits that are buried in the ground), have specific physical requirements. One requirement is ovalization, a measure of how round, or oval the outer surface of a conduit is. Because conduits needs to be coupled together to form longer sections of conduit, the conduit must be able to fit into standard couplings. The mathematical equation for calculating ovalization is (OD stands for outer diameter):((Max OD−Min OD)/(Max OD+Min OD))×200
The industry standard is to have less than 7% ovalization. The typical method to correct ovalization in the industry is to extrude a thicker walled conduit and then stretch the conduit more down to the desired wall and outer diameter thickness.
In the case of a divided conduit, where a strip-shaped substrate is introduced into the conduit during extrusion (and therefore the edges of the strip-shaped conduit are embedded into the walls of the conduit), the addition of the fabric resulted in ovalization of greater than 7%. The standard ovalization industry fix did not improve the ovalization. Thus a need exists, for an extrusion die and a process to create a divided conduit having improved ovalization.